The broad goal of this project is to study the levels of the changing (with time) ratio of fat to fat-free tissue in a selected group of diabetics, by quantitative, absorptiometric, in vivo measurements done over a three-year time base. The purpose will be to establish a time-related change in the lipid-lean ratio at a representative point on the body, and to establish an index of change related to disease by correlating the quantitative lipid measurements with clinical information. This investigation will be carried out by applying the dual beam differential absorption principle, which has been developed in this research laboratory using the radioactive isotope 109Cd with photon radiations at 88 keV and 22 keV, to accurately measure the total soft tissue fat fraction (subcutaneous, plus deep-lying) in a cross-section of the upper arm at the triceps muscle mid-point. This analytical system may be safely used and repeated in vivo. It is a unique measurement principle that will provide the fat fraction of soft tissue in vivo with precision and accuracy of 2% or less. In addition to the stated goal, the time dependence of the lipid value in living tissue will be explored with respect to other selected diseases, such as Cushing's, muscular distrophy, idiopathic cyclic necrosis, lymphodema and other, as patients become available for study. The aim of this secondary goal will be to investigate in a preliminary way the usefulness of this quantitative, analytical adiposity measurement in particular disease states in which lean to lipid may change and specifically its possible contribution to prediction of the course of disease by an accurate assay of adiposity. Developmental studies here, with this 109Cd dual beam absorptiometry principle both in vivo and in vitro, have established its accuracy and precision. Preliminary analytical measurements of adiposity of staff volunteers, and with over two hundred other subjects, have demonstrated the practicality and preliminary anthropomorphic correlations of the methodology. This project will be a collaborative research program carried out between the HFH Metabolism Clinic under the direction of F. Whitehouse, MD., and the Radiation Physics Research Laboratory under the supervision of L. Preuss.